Turbulent flow drill collar

ABSTRACT

A tubular drill string member having grooves formed in the outer surface thereof extending circumferentially thereabout and longitudinally thereof. The grooves include short sections or lengths of first groove portions which generally parallel the longitudinal centerline of the tubular drill string member or drill collar and short sections or lengths of second groove portions which are inclined generally 15* relative to a plane normal to the longitudinal centerline of the drill collar. The second groove portions interconnect the adjacent ends of adjacent first groove portions and the first and second groove portions of each groove are disposed generally in a helical path extending along and about the corresponding drill collar.

United States Patent lnventor Appl. No.

Filed Patented Assignee Nolen A. Yount Beeville, Tex.

July 3, 1969 Jan. 12, 1971 W. E. leds Beeville, Tex. a part interest TURBULENT FLOW DRILL COLLAR 5 Claims, 3 Drawing Figs.

US. Cl.

Int. Cl.

References Cited UNITED STATES PATENTS 9/ 1964 Fox 3,175,374 3/1965 Toelke FZlb 17/00 Field ofSenrch ill 3,338,069 8/1967 Ortloff 64/1 3,360,960 1/1968 Massey 64/1 FOREIGN PATENTS 206,517 2/1909 Germany 175/320 Primary Examiner-James A. Leppink Attorneys-Clarence A. OBrien and Harvey B. Jacobson ABSTRACT: A tubular drill string member having grooves formed in the outer surface thereof extending circumferentially thereabout and longitudinally thereof. The grooves include short sections or lengths of first groove portions which generally parallel the longitudinal centerline of the tubular drill string member or drill collar and short sections or lengths of second groove portions which are inclined generally 15 relative to a plane nonnal to the longitudinal centerline of the drill collar. The second groove portions interconnect the adjacent ends of adjacent first groove portions and the first and second groove portions of each groove are disposed generally in a helical path extending along and about the corresponding drill collar.

tion of the drilling stringimmediately above the drilling bit.

A drill collar is made in various 1 diameters and wall thicknesses whereby the in eight of the drill collarper-unit of its length may vary greatly. Because Jdrilling bits have been greatly improved it is now possible to increase the weight on the drillingbit so as toincrease the rate of penetration of the bit. The weight on thebit is controlled,.t o a great extent, by the size and number of drill collars disposed above the bit. As additioiial drill'collars are added to the bottom end of a drill stri'ng,ythe friction of the drill collars in the well bore is increased The outerdiaineter ofthe collars used isless than the outside diameter of the associated drill bit whereby drilling fluid or mud being pumped'through the drill bit is permitted to move upwardly in the well bore about theldrill collars toward the upper end of the well bore.

It has been found desirable at times to decrease the opening in the drillingbit through which the drilling fluid passes resulting in a decrease in the amount-of drilling fluid which may pass "to ball or stick together. This can increase hydrostatic pres-' sure in the well bore and the increase'in hydrostatic pressure can cause a breakdown in. formation porosity and loss of drilling fiuideWhen drilling fluid loss is experiencedthere is a great possibility of sticking the drilling string in the hole. A stuck drilling string is freedonly after expensive fishing jobs and it sometimes causes a well to blow out.

The object of this invention is to :provide a drill collar serving to create a turbulent flow of drilling fluid about the drill collars during return of the drilling fluid to the upper end of the well bore. This turbulent flow. will increase the speed of the drilling fluid and the-cuttings as they move toward the upper end of the bore and it willkee'p the drilling cuttings from balling up-and sticking. Further, it will decrease the hydrostatic pressure 'inthe bore.

Another object of this invention is to provideatubular drill collar which will serve to prevent mud cake from buildingup in the well bore throughout a formationwith porosity.

The turbulent flow -drill'collar of the instant invention further has as its objects the general objects of :a drill collar such as thatdisclosedin US. Pat. No, 2,999,552.

A final object: "of this invention to be specifically 'enumerated herein is to provide a drill collar in accordance with the precedingobjectsand which will conform to conventional forms of manufacture, be-of simple construction and easy to use so as to provide a'device that will be economically feasibIeJong lasting and relatively trouble free in operation.

These together with other objects and advantageswhichwill become subsequently apparent "reside :in .the details of con: struction and operation .as more fully hereinafter described and claimed, reference being had to the accompanying drawing'siforming a-part hereof, wherein-like numeralsrefer to likespartsthroughout, andlin which;'

FIG. 1 is anelevationalviewof the improveddrillcollar of the instant invention with portions of the upper end thereof being broken away and illustrated in vertical section;

FIG. ,2 :is an enlarged fragmentary vertical sectional :view taken substantiallyupon the plane indicated by the section line2-2 ofFlG. l; and t Y 3 FIG. 3 is an enlargedvhorizontal sectionalview taken sub FIG. 1.

Referring now more specifically to thedrawings, the nu rrieral 10 generally designates the drill collar of the instant in= vention. The collar 10 is generally conventional in that one end thereof is internally threaded as at '12 and the other end thereof is externally threaded as at l4. However, the collar 10 includes a pair of grooves referred to in general by the reference numerals 16 and 18 which extend along and about the drill collar 10 in generally helical paths. Each of the grooves 16 includes first groove portions 20 and second groove portions 22. The first portions 20 generally parallel the longitudinal center line of the drill collar 10 and the second groove potions are inclined approximately l5 relative to a plane normal to the longitudinal center line of the drill collar 10. Each groove portion 22 interconnects the adjacent ends of a pair of adjacent first groove portions 20 and in this manner substantially all portions of the grooves 16 and 18 either generally parallel or are disposed substantially normal to the direction of movement of adjacent peripheral portions of the drill collar during rotation of the latter.-

As can best be seen from FIGS. 2 and 3 of the drawings the cross-sectional shape of the groove portions 20 and 22 is dissimilar. The groove portions 20 are substantially V-shaped in cross section including a pair of relatively inclined opposite sidewalls 26 and 28. The groove portions 22 also include relatively inclined opposite sidewalls 30 and 32, but the inner marginal edge portions of the sidewalls 30 and 32 are connected by a bottom wall 34.

it will be noted that the relatively inclined sidewalls 26 and .28 of the groove portions 20 do not offer any edges which would tend to cause displacement of the associated drill string in either longitudinal direction upon engagement of the portion of the drill collar 10 about one of the grooves 20 with the walls of the well bore during rotation of the drill collar 10. Further, the groove portions 22 are free of cutting edges and are short in circumferential extent, whereby any tendency of the grooves 22 to longitudinally displace the drill collar 10 during rotation of the latter by contact with the well bore will be brief.

The groove portions 22 are inclined l5 relative to a plane normal to the longitudinal center line of j the drill collar although the inclination of the groove portions 22 may vary 2 or 3, or possiblymore, above and below an inclination of 1 5.

The particular configurations of the grooves 16 and 18 prevent the drilling cuttings fromballihgupziiid sticking by increasingthe turbulence of the drilling fluid as it passestoward the top of the well bore. Further, the hydrostatic pressure of the drilling fluid within the well bore ;is reduced and mud cake is prevented from building up in the well bore. Also, "the for mation of the grooves 20 and 22 provide-a means to insure that drilling fluid is disposed on all sides ofthe drill collar Ill. Thus, the drill collar -10 is lubricated and any tendeneyfor the drill collar to stick in the-well bore is reduced.

Furthergby having thegroove portionsi20 parallel the lam gitudinal axis of thedrill collar 10 and the groove portions 22 disposed substantially normal to the longitudinal axis of the drill'collar" 10, there are nooutersurfaceportions-of the drill collar which would tendto cause rotation of the lowerend of the drill string as it is being lowered into the bore. it is not unusual for drill strings having drill collars thei'eofprovidedwith smoothly curving helical grooves to cause apor'tioti of-the drilling string to be unthreaded while the drill string-isbeiiig lowered into the well bore. Whe'n'this happens, the lower end of the drilling string drops to the bottom of the wellboi-e and must be retrieved by specific fishing tools lowered into the bore.

By having the grooves 16 and 18 "steppedg" tliere is-sub= stantially no tendencyfor the lower end of-the drillingstringte unscrew from the upper end of-the drilling string asthestring' is being lowered into the well and; portions ofthe loweriend of the string contact the wellbore.

The foregoing is considered as illustrativeonlyof tl'i'e'ir'rinei= ples of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, i't is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.

I claim:

1. An elongated upstanding tubular member for connection in a drill string, said Lubular member having at least one generally helical groove in its outer peripheral surface, said groove including alternating first and second groove portions whose adjacent ends are communicated, said first groove portions generally paralleling the center line of said tubular member and said second groove portions being inclined generally relative to a plane normal to said center line said groove portions being each of a length less than the outside diameter of said tubular member, the lower sidewall portions of the second groove portions being generated by a spirally displaced radius of said tubular member and the upper sidewall portions of said second groove portions being upwardly and outwardly inclined.

2. The combination of claim 1 wherein said first groove portions are generally V-shaped in cross section.

3. The combination of claim 1 wherein said second groove portions are generally trapezoidal in cross section.

4. The combination of claim 3 wherein said first groove portions are generally V-shaped in cross section, the sidewalls of said first groove portions being inclined less than 45 relative to radii of said tubular member passing through said groove portions.

5. The combination of claim I wherein the outer surface portions of said tubular member through which said groove portions open are generally cylindrical. 

1. An elongated upstanding tubular member for connection in a drill string, said tubular member having at least one generally helical groove in its outer peripheral surface, said groove including alternating first and second groove portions whose adjacent ends are communicated, said first groove portions generally paralleling the center line of said tubular member and said second groove portions being inclined generally 15* relative to a plane normal to said center line said groove portions being each of a length less than the outside diameter of said tubular member, the lower sidewall portions of the second groove portions being generated by a spirally displaced radius of said tubular member and the upper sidewall portions of said second groove portions being upwardly and outwardly inclined.
 2. The combination of claim 1 wherein said first groove portions are generally V-shaped in cross section.
 3. The combination of claim 1 wherein said second groove portions are generally trapezoidal in cross section.
 4. The combination of claim 3 wherein said first groove portions are generally V-shaped in cross section, the sidewalls of said first groove portions being inclined less than 45* relative to radii of said tubular member passing through said groove portions.
 5. The combination of claim 1 wherein the outer surface portions of said tubular member through which said groove portions open are generally cylindrical. 